Heretofore respiratory masks having exhaust devices attached thereto have been known. For example, see U.S. Pat. Nos. 3,130,722; 3,955,570; 4,019,508; and 4,055,173 and Swiss Pat. No. 556,664.
The prior art mask devices typically cover the wearer's entire face. See U.S. Pat. Nos. 3,955,570; 4,019,508; and 4,055,173 and Swiss Pat. No. 556,664.
U.S. Pat. No. 3,130,722 is directed to a respiratory mask which does not cover the entire face of the wearer. The mask shown in this patent includes an apex which is generally formed over the wearer's nose. The apex of the mask is generally V-shaped in both the horizontal and vertical cross-sections and positioned directly above the nose. The mask also includes a port which allows ambient air to pass through the mask and into a cavity defined by the apex of the mask over the wearer's face.